Nanosized LiSrPO4:Eu2+ phosphor with blue-emission synthesized by the sol–gel method

A novel nanosized phosphor, LiSrPO4:Eu2+, was prepared by the sol–gel method with a precursor (Li/Sr/Eu) polymerized citrate–polyethylene glycol, calcined at 950 °C for 3 h in a weak reductive atmosphere of active carbon. X-ray diffraction results confirmed the formation of LiSrPO4:Eu2+. Field-emission scanning electron microscopy observation showed an average diameter of about 15 nm for the particles with a spherical-like morphology. Photoluminescence measurements results indicated that upon excitation with 346 nm light, the nanosized LiSrPO4:Eu2+ showed intensely blue-emission peaked at about 445 nm. Compared with the microsized phosphor obtained by the solid-state reaction method, the main peaks in the emission and excitation spectra of the nanoparticles shifted to shorter wavelength, and the nanoparticles exhibited longer decay time. The symmetric emission band shape implies that Eu2+ ions just occupy one kind site in the LiSrPO4 lattice by substituting Sr2+ ions.